Department of Psychiatry and Psychotherapy, University of Freiburg Medical School, Hauptstrasse 5, D-79104, Freiburg, Germany.
VivaCell Biotechnology GmbH, Ferdinand-Porsche-Strasse 5, D-79211, Denzlingen, Germany.
Sci Rep. 2017 Mar 8;7(1):116. doi: 10.1038/s41598-017-00225-5.
Exaggerated inflammatory responses in microglia represent one of the major risk factors for various central nervous system's (CNS) associated pathologies. Release of excessive inflammatory mediators such as prostaglandins and cytokines are the hallmark of hyper-activated microglia. Here we have investigated the hitherto unknown effects of capsaicin (cap) - a transient receptor potential vanilloid 1 (TRPV1) agonist- in murine primary microglia, organotypic hippocampal slice cultures (OHSCs) and human primary monocytes. Results demonstrate that cap (0.1-25 µM) significantly (p < 0.05) inhibited the release of prostaglandin E (PGE) 8-iso-PGF and differentially regulated the levels of cytokines (TNF-α, IL-6 & IL-1β). Pharmacological blockade (via capsazepine & SB366791) and genetic deficiency of TRPV1 (TRPV1) did not prevent cap-mediated suppression of PGE in activated microglia and OHSCs. Inhibition of PGE was partially dependent on the reduced levels of PGE synthesising enzymes, COX-2 and mPGES-1. To evaluate potential molecular targets, we discovered that cap significantly suppressed the activation of p38 MAPK and MAPKAPK2 (MK2). Altogether, we demonstrate that cap alleviates excessive inflammatory events by targeting the PGE pathway in in vitro and ex vivo immune cell models. These findings have broad relevance in understanding and paving new avenues for ongoing TRPV1 based drug therapies in neuroinflammatory-associated diseases.
小胶质细胞过度炎症反应是各种中枢神经系统(CNS)相关疾病的主要风险因素之一。大量促炎介质如前列腺素和细胞因子的释放是小胶质细胞过度激活的标志。在这里,我们研究了辣椒素(cap)——瞬时受体电位香草酸 1(TRPV1)激动剂——对原代小鼠小胶质细胞、器官型海马切片培养物(OHSCs)和人原代单核细胞的未知作用。结果表明,辣椒素(0.1-25 μM)显著(p < 0.05)抑制前列腺素 E(PGE)8-iso-PGF 的释放,并差异调节细胞因子(TNF-α、IL-6 和 IL-1β)的水平。药理学阻断(通过辣椒素和 SB366791)和 TRPV1(TRPV1)的基因缺失并不能阻止 cap 介导的激活小胶质细胞和 OHSCs 中 PGE 的抑制。PGE 的抑制部分依赖于 PGE 合成酶 COX-2 和 mPGES-1 的水平降低。为了评估潜在的分子靶点,我们发现 cap 显著抑制了 p38 MAPK 和 MAPKAPK2(MK2)的激活。总之,我们证明 cap 通过靶向体外和离体免疫细胞模型中的 PGE 途径来减轻过度炎症事件。这些发现对于理解和为基于 TRPV1 的神经炎症相关疾病的药物治疗开辟新途径具有广泛的意义。